1. Field Of The Invention
The invention relates to a novel process for the preparation of pentaalkylchromenes of the general formula: ##STR2## wherein R denotes a lower alkyl group having 1 to 4 C. atoms and R.sub.1 denotes a phenyl group which is unsubstituted or substituted by a lower alkyl group having 1 to 4 C atoms, by halogen or by a nitro group or an alkanoyl group having 1 to 4 C atoms, and to novel intermediates occurring in the process.
Pentaalkylchromenes, in particular tetramethylchromenes, are useful intermediates for the preparation of, for example, hypolipidaemic pharmaceuticals [J. Med. Chem., 32, (1989)).421-428].
2. Background Art
European Published Patent Specification No. 139,421 discloses the preparation of corresponding pentaalkylchromenes by condensation of an acetylhydroquinone with alkoxy- or aryloxyacetone derivatives and by reduction of the resultant chromanone. This synthesis has the disadvantage that even the starting materials are accessible with difficulty, and additionally further steps are necessary after the condensation in order to obtain the desired pentaalkylchromene.